1. Field of the Invention
The present invention relates to a particle producing method and a particle producing apparatus, and more particularly to a particle producing method and a particle producing apparatus for preparing particles in a gas phase using the gas phase reaction.
2. Description of the Related Art
A particle of nanometer size has a large specific surface area (surface area per unit volume) and has a function such as the quantum size effect, which is not provided conventionally. The particle of nanometer size is drawing attention as a substance of new conformation in recent years. The particles of nanometer size are applied to a catalyst, a battery electrode, a visible LED element and a phosphor of display, depending on the kind of particles.
A method for producing particles and a method for controlling the particle size have been described in JP-A-2001-261335.
JP-A-2001-261335 discloses a configuration in which a reaction container has a source gas introduction portion and a surface-adhesion introduction portion separately. Particles are grown while a source gas and a carrier gas are flowed through the reaction container, and produced particles are collected from the opposite side to the source gas introduction portion.
The particles are grown while moving along with the carrier gas within the reaction container.
As a method for producing the particles of desired size, the collected particles may be sieved through a filter. Alternatively, a surface adhesion maybe blown onto the particle surface to compulsorily stop the growth. For this purpose, the surface-adhesion introduction portion is provided on a side of the reaction container.
In the conventional particle producing apparatus with the above configuration, the particle size was controlled depending on timing when the surface adhesion was introduced during growth of particles. Therefore, to obtain particles of a predetermined size, it was necessary to provide the surface-adhesion introduction portion, which was different from the source gas introduction portion (a source gas introduction port).
Moreover, to produce particles of different sizes, it was required to move the surface-adhesion introduction portion (a surface-adhesion introduction port). Alternatively, it was required to provide a plurality of surface-adhesion introduction portions.
Also, even if the surface-adhesion introduction port was shifted, gases in the reaction container had different flow rates and thus, it was difficult to obtain only particles of desired size. To control the size of produced particles means to remove particles of undesired size through the filter. This results in a great influence on the production efficiency.